Nearctic species of Pandivirilia Irwin and Lyneborg (Diptera: Therevidae: Therevinae)

The genus Pandivirilia is widespread across the Nearctic and Palaearctic regions. The Nearctic species are redescribed, including the description of two new species: Pandivirilia constricta Webb and P. rufa Webb. Their phylogenetic position among the Palaearctic species and related higher therevine genera is elucidated by cladistic analysis of male and female morphological characters. A key to the Nearctic species is provided along with maps of their distribution. A Deotype is designated for P. albifrons (Say) and a lectotype is designated for Psilocephala limata Coquillett. Also, Dichoglena melampodia (Loew), Ps. conspicua (Walker), and Spiriverpa nitoris (Coquillett) are placed as new combinations within Pandivirilia. P. bussi (James) is placed as a new combination within Cliorismia, making this genus Holarctic in distribution. Ps. canadensis Cole, Ps. limata Coquillett, and Ps. pollinosa Cole are placed in synonomy under P. conspicua (Walker), P. argentifrons Cole is placed in synonomy under P. melampodia (Loew), and Thereva borealis Cole is placed in synonomy under P. albifrons (Say).